The present invention relates to a movable shield and containment system for the maintenance of existing bridges and, more particularly, to a xe2x80x9csafety tunnelxe2x80x9d which is movable with respect to the bridge structure to facilitate traffic flow along the roadway of the bridge (and/or under the bridge) while protecting the traffic flow from falling debris during the maintenance work on the bridge.
Existing bridges require substantial maintenance. The maintenance is required at least periodically, if not continuously. For example, it is often necessary to remove the paint (such as a lead-based paint) from the steel structure of a bridge prior to applying a new coating thereto. To remove the paint, conventional sand-blasting or shot-blasting equipment is used. Suitable available measures are taken (as hereinafter discussed) to prevent the debris from falling onto the roadway, or into any water below the bridge, or otherwise polluting the environment.
At the same time, it is also very desirable to facilitate the continuous traffic flow along the roadway, while the maintenance is being performed, and thus avoid a complete shutdown of the traffic flow. While the traffic flow is primarily vehicular or railway traffic, it is also desirable to maintain any pedestrian traffic as well as facilitate access for the maintenance crews. By maintenance, it is understood that any repair or construction on the bridge is contemplated herein.
To maintain the traffic flow while the maintenance is being performed, the prior art has resorted to the use of a shield and containment structure (commonly referred to as a xe2x80x9ctraffic shieldxe2x80x9d) constructed within or under the bridge, along a given length thereof, and above the deck or roadway of the bridge.
This conventional traffic shield, together with the roadway, provides a complete enclosure for the traffic flow (which may be vehicular, railway, pedestrian or some combination thereof). Within the traffic shield (or thereunder) the traffic is protected against any falling debrisxe2x80x94such as paint chips from the bridge, the materials of shot blasting or sand blasting, and any tools, components or structural elements accidentally dropped by the maintenance workers. By the same token, the workers are protected against the vehicular or rail traffic. As a result, a complete shut-down of the bridge is avoided, and the traffic flow is substantially unimpeded while the maintenance is being performed.
However, when the maintenance has been completed on a given length or section of the bridge, the traffic may be halted for a substantial period of time sufficient to enable the workers to completely dismantle the traffic shield, move its individual components to the next successive section of the bridge, and then re-assemble the traffic shield therein. This is time-consuming, hence expensive, and causes a substantial traffic problem; and a need exists for a more efficient solution to this long-standing problem.
Accordingly, it is the primary object of the present invention to alleviate the disadvantages and deficiencies of the prior art by providing a movable safety tunnel within the bridge, thereby resulting in a substantial cost-savings and, concurrently, holding the inconvenience to the motorists to an absolute minimum.
The present invention finds particularly utility for use in connection with a bridge having a roadway for vehicular and/or pedestrian traffic, wherein maintenance is being performed on the bridge, and wherein a safety tunnel is constructed within a respective longitudinal section of the bridge. Accordingly, the traffic flows on the roadway of the bridge substantially uninterrupted while the maintenance is being performed on the respective longitudinal section of the bridge. More specifically, the traffic on the roadway of the bridge is protected against falling debris, such as paint particles, materials for shot blasting or sandblasting, tools, components and the like. At the same time, the workers performing the maintenance are shielded from the traffic flow. Once the maintenance on the respective longitudinal section of the bridge is completed, the traffic shield is normally dismantled and thereafter reconstructed on a next adjacent longitudinal section of the bridge.
In the improvement of the present invention, the traffic shield comprises a safety tunnel which is movable along the length of the bridge.
As a result, the necessity for repeatedly dismantling and reconstructing a conventional traffic shield is eliminated (as the maintenance on the bridge progresses along the length of the bridge).
For example, and in comparison to the prior art, if the bridge is sixteen hundred (1600) feet long, and if the conventional traffic shield is one hundred (100) feet long, it will have to be assembled, disassembled and re-assembled approximately sixteen (16) times. Thus is time-consuming and expensive and a distinct inconvenience, repeatedly, for the vehicular traffic on the bridge. With the present invention, however, the safety tunnel may be rolled from place to place along the bridge without requiring the safety tunnel to be taken apart.
In a preferred embodiment of the present invention, rails are constructed on top of the respective parapets running along the respective sides of the deck or roadway of the bridge, and the movable safety tunnel has a trolley system riding on the rails.
The trolley system is locked to a respective longitudinal section of the rails as the maintenance is being performed on a corresponding respective length of the bridge; and the trolley system is unlocked from the respective longitudinal section of the rails to enable the safety tunnel to be moved to the next adjacent section of the bridge on which the maintenance is to be performed. The safety tunnel is pushed and/or pulled by a tow truck (or other suitable piece of equipment) to the next adjacent section of the bridge.
Preferably, the trolley system comprises a plurality of respective spaced-apart trolley assemblies.
In the preferred embodiment, the safety tunnel includes an inverted U-shaped structure having a roof assembly joined to respective sides depending therefrom. These respective sides have lower portions carried by the plurality of trolley assemblies riding on the respective rails.
These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the enclosed drawings.